Conventional dressings for use on salads, especially those in use in Mediterranean countries, are emulsions of an oil phase (e.g. 50-60%) in a water phase (containing vinegar), optionally further containing salt, herbs, and spices. As the size of the oil droplets in these dressings is around 0.2-5 mm it is easily visible by the eye that oil is present. Such dressings are conventionally prepared fresh by the housewife by shaking or stirring oil (40-70%), vinegar (60-30%) and optionally salt, herbs together, to give a translucent, emulsified but not very stable salad dressing. Such dressing will generally be used directly after mixing and before phase separation occurs. Similar formulations are also commercially available but give rise to phase separation and/or the formation of creamy, turbid layers.
As a convenient alternative, there are available ready-to-use salad dressings which are in the form of a stable fine emulsions of oil and water, having an opaque, milky appearance, with no oil visibly present (either as droplets or as a separate layer).
Yet other type emulsions (having more coarse oil droplets) are disclosed in GB 2 143 114. Herein, salad dressings containing 10-50% oil, 0.1-0.4% gum arabicum, 0.3-0.7% iota-carrageenan and water are described. Said composition is processed to form an emulsion using emulsifying apparatus. It is reported the so-prepared emulsion is stable for at least several months. In order for such emulsions to be stable, either high levels of emulsifiers and stabilisers need to be used or the amount of oil which can be emulsified in the water in a stable manner is restricted, e.g. to 50% or less. If low levels of emulsifiers or stabilisers are used or high levels of oil, phase separation is likely to occur. Although such dressings may be convenient in use, they are generally perceived by the customer as artificial, as no oil can readily be seen as a separate layer (the visible presence of oil is seen as a quality attribute in dressings).